(a) Field of the Invention
This invention relates to the construction of modular buildings and more particularly relates to multistory buildings formed by stacking preformed modules.
(b) History of the Prior Art
The construction of multistory buildings using construction modules is well known in the art. Examples of patents relating to such construction are numerous and include U.S. Pat. Nos. 3,694,977; 3,703,058; 3,721,052; 3,758,998; 3,919,812 and 4,129,968.
All of the foregoing patents relate to modular building construction and with the exception of U.S. Pat. Nos. 3,919,812 and 4,129,968 relate to multistory modular construction.
In the prior art, modular construction has been found to have various serious disadvantages. In particular, it has been felt that construction of finished modules for such modular construction should occur at a fixed factory location in order to obtain the benefits of assembly line manufacture. Such fixed location construction, however, has not been as efficient as desirable. Part of this inefficiency is due to the fact that finished modules must be transported from the fixed site to the construction site. Unless the modules were of small width, e.g., less than about 10 feet, such modules could not be transported on the highways and even when the modules were less than 10 feet, special regulations and procedures often had to be followed for transporting wide loads. The transportation costs involved in the transport of finished modules have therefore been much higher than desirable. Alternatively, when modules were made of a sufficiently narrow width to avoid special transportation problems, modules had to be joined at the construction site in order to obtain room sizes wider than about 8 feet.
Another problem involved with modular construction of multistory or high rise buildings has been that either the modules had to be constructed in such a way that they were not only self-supporting but could support modules placed at upper levels or alternatively independent super structures had to be built in order to support the modules. When the modules were constructed of sufficient strength to support upper modules levels, the bases and walls of the modules were generally constructed of reinforced concrete or steel or both. An example of unfinished modules having concrete bases and sidewalls are those sometimes formed on site by prior art tunnel forming (described in Construction Contracting, June 1980, pages 24-28). Such modules have great weight thus creating additional transportation difficulties when constructed at a plant or factory having a fixed location. Furthermore, when the walls of the modules were in the form of reinforced concrete, interior finishing of the modules was made more complicated since special procedures had to be followed to provide interior wall surfaces which did not have the cold feeling or nature of concrete surfaces. Furthermore, such concrete surfaces were difficult to insulate.
When the optional method of constructing super structures to hold the modules was used, the construction costs and difficulty dramatically rose due to the problems and the materials associated with super structure construction.